PROJECT SUMMARY: ABSTRACT Observational evidence has linked excessive added sugar intake with diseases such as obesity, diabetes, and heart disease; thus, strategies to reduce added sugar intake are a clear public health priority. To determine if an individual is consuming too much added sugar, dietary recall is typically used; while they are the gold standard for dietary assessment, they are subject to challenges. Objective dietary intake measures are needed to investigate associations among intake, behaviors, and health outcomes. Prior research indicates that carbon-13 relative to carbon-12 [?13C] in hair is a biomarker that reflects free-living intake of added sugar derived from corn and cane. However, studies are needed with more racially/ethnically diverse populations that include children younger than 6 years of age and that are sufficiently powered to analyze the influence of the sex of the child. Reports suggest maternal parenting practices surrounding foods, especially sweets, vary between sons and daughters, which in turn could contribute to differences in added sugar intake. This cross- sectional study will determine for the first time variation in ?13C among a racially diverse group of 3- to 7-year- old boys and girls in the context of their mothers?the caregivers who not only provide the foods but also teach children the social and cultural meaning of sweet foods in the home. We will take a multipronged, rigorous approach that (a) incorporates children?s sex as a biological variable, (b) uses state-of-the-art diet assessment and analysis measures with the expertise of PhD-level Registered Dietitians to determine added sugar intake and diet, and (c) uses validated methods to assess sweet taste phenotypes (e.g., level of sweetness most preferred, sweet food liking). By phenotyping both mothers and their children, we will determine intake variation both within and between dyads; the level of concordance among diet, sweet taste phenotypes, and ?13C; and whether these factors differ by the sex of the child. The proposed study will provide me with the needed training in human psychophysical taste testing procedures, dietary biomarker assessment, experimental method and design, and scientific underpinnings of ontogeny of chemical senses, and build the foundation needed to transition to an independent scientist conducting inter-disciplinary work in the chemical senses and nutrition relevant to the mission of the NIDCD.